Just wanted to say I fixed it with these commands and firmware if anyone is interested. I tried everything else including flashing with twrp and wiping all caches and it didn't work, getting the stock firmware and doing it like this worked to clear boot screen endless stuck
download fastboot and adb and xoom drivers 6.4 (about 5mb) and the appropriate stock firmware. for me it was ZM604
at the command type
adb reboot bootloader
you may need to unplug and replug cable after it goes in fastboot mode.
.. should return something "02a439cj0skjdke fastboot" to proceed.
fastboot oem unlock
.. look at your tablet and follow the instructions, for me it was down twice and up once to accept unlock conditions, then it reboots
on reboot press vol down 2 seconds after you see moto logo, it will enter fastboot
fastboot flash boot boot.img
fastboot flash system system.img
fastboot flash recovery recovery.img
fastboot flash userdata userdata.img
fastboot erase cache
fastboot erase userdata
no need to relock after, you will see android logo and first boot pop up after 2-3 mins